{ INFORMATICS.MCCME.RU
  Problem statement: http://informatics.mccme.ru/moodle/mod/statements/view3.php?chapterid=206
  Verdict: Accepted
}
var a,b,i,j:longint; c:array[0..20,0..20] of longint;
begin
Assign(input,'input.txt');
Assign(output,'output.txt');
reset(input);
rewrite(output);
read(a,B);
fillchar(c,sizeof(c),0);
c[1][1]:=1;
for i:=1 to a do begin
    for j:=1 to b do if c[i][j]=0 then c[i][j]:=c[i-1][j]+c[i][j-1];
end;
writeln(c[a][b]);
end.